noun(pluralpropylaea)Etymology: Latin, from Greek propylaion, from pro- before + pylē gate — more at pro-Date: circa 1706
a vestibule or entrance of architectural importance before a building or enclosure — often used in plural

Propylaeum — Prop y*l[ae] um, n.; pl. {Propyl[ae]a}. [L., fr. Gr. ?; ? before + ? a gate.] (Anc. Classical Arch.) Any court or vestibule before a building or leading into any inclosure. [1913 Webster] … The Collaborative International Dictionary of English

propylaeum — [präp΄ə lē′əm] n. pl. propylaea [präp΄əlē′ə] [L &LT; Gr propylaion, orig. neut. of propylaios, before the gate &LT; pro , before + pylē, gate] Class. Archit. an entrance, vestibule, or portico before a building or group of buildings … English World dictionary